Had my head cleaned at a local shop today prior to my intentions of grinding the carbon off the valves, lapping them, and reassembling…. The shop advised me that my head had a small crack…. Water jacket, #6 exhaust side as per photo….
The guy at the shop advised me that his approach would be to drill a small 1/8” hole at the end of the hole to stop further spread, file out a groove down the length of the crack, and then fill it all with JB Weld…. He said that it would be unlikely to find a shop that would weld on old aluminum due to contamination from oil etc…. Seems like a simple solution, is this a valid approach? If not then what?
My head had corrosion around the water channels and the shop I took it to had no problem building them up by welding, they then heated and straigtened the head before machining. Your head seems to already have had a weld repair from the photo. Definately grind out the crack though.
Mine was worse.
There would not be any oil contamination there in the water passage. There will be corrosion. An expert welder can do that job. The method is to use a die grinder to open up that crack into a 1/8" groove, eliminating corroded metal and getting down to clean metal, then immediately filling the groove with a TIG welder and rod, or a MIG welder with an aluminum wire spool gun as I have will work, while keeping the weld bead from getting too hot, then use a router or hand file to dress the surface.
A good welder can take care of that likity-split. The water passages, in your head are nice and oval. In mine, the ovals had taken the shape the maps of our continents. But now they are nice and oval again, thanks to our go-to welder here in Berkeley.
John, I’m in the bay area like you. Who would that welder be so I can add them to my list of future contacts should the need arise for such a specialist operation? Thanks.
Hi Chris. Dennis Echeverry and Dan Marvin at Norman Racing; Fourth Street off Gilman… Dennis welds it and Dan decks it. Come to think of it, they did my 3.4L head about 30 years ago.
As others of said, a good welder could take care of this, no problem. The stop drilling is critical, and it looks like this head has been repaired before.
I have found a welder with good experience , bit of a challenge in my part of the world, basically had to follow a trail from one word-of-mouth shop to another until I got the right guy. I’ll be dropping the head of tomorrow and hopefully he won’t find anything else that needs repairing……
Dave, might not be a bad idea to talk someone like Dennis and get educated on the process, then later quiz your welder to see if he operates on the premise.
Well time continues to creep by! A job that would have taken a couple of weekends a few years ago is closing in on 6 months! Parts are further away, and skilled machine shops are harder to find….
In any event, crack has been welded as well as the water jacket opening in the same location rebuilt, extreme amount of carbon build up removed from pistons, valves, cylinder head passages, Valves lapped and clearances reset, all studs and nuts chased and replaced as necessary… so time to put the head back on, and here’s the question…
All the info I have read advises to install the head complete with camshafts, intake manifold and carbs, and exhaust manifolds attached…. This creates a pretty heavy and unwieldy assembly to install when the engine is still in the car and the bonnet is still mounted… personally I’d prefer to remove the camshafts to ensure no valves are at risk, and leave everything else off until the head has been mounted…. Is there a reason not to do it this way? Why have everything else attached first?
Thanks!
Also will be adding the Fan Shroud that was non-existent and a new Fan so hopefully that will help with cooling, and another post I had about my timing marks on flywheel vs pulley being different I have now determined were actually caused by an additional layer of info as my exhaust camshaft was a few degrees out of proper rotation… so depending on what point I used to start my measurements I kept getting different results… expecting this old girl to really come to life after all this love!
I do it that way. Put the engine at TDC, with distibutor rotor pointed at #6. Install cams with the checking slot up, Control cam tendency to rotate when tightening cam bearings with a vise grip on the shaft
Doug
I would probably prefer to have the intake manifold, and possibly carb bodies installed, as on some cars, its hard to access these nuts. I always leave the exhaust manifold until last
I also prefer to lower (and remove) the head via engine crane or block & tackle if I have to do it on my own, even when I was younger & stronger
That’s interesting, I was thinking that the lower nuts on the exhaust manifold would be the hardest to install with the head already on the block, the intake side should be easy just unsure if there will be clearance from the inner panels to slide the intake manifold over the long studs ….
the lower manifold bolts can be an an issue, RHD is worse
I personally find it very quick and easy to remove or install an exhaust manifold from the head in situ, 15 mins. 1/4" drive gear, and 1/2" open end spanner, nice new studs and nuts presumably, and I anti-seize them
and answered my own question by actually referring to the service manual, which clearly tells how to remove and refit both the exhaust manifold and the intake manifold while the head is in the car…
I would avoid fitting the cams with the head already fitted. No point taking the risk that valves will tangle with each other or the pistons, as they surely will during a moment’s inattention.
If this is your first Jag rebuild it is better/safer IMO to have the head supported at each to hold it clear of the bench and install the cams in the TDC position without rotating. Then with the crank also at TDC (#1 and #6) install the timed head and fit the cam sprockets, all without rotation.
It is possible to use other methods but riskier and less forgiving, as several here have found…
